The present disclosure relates to an image forming apparatus that is equipped with an air cooling mechanism for cooling components (cooled units) during use.
In an image forming apparatus (laser printer), a toner pattern that is patterned corresponding to an exposed portion is formed on the surface of a cylindrical photosensitive drum. Then, this pattern is temporarily transferred to an intermediate transfer belt, and thereafter transferred to a medium (paper). In order for this, the photosensitive drum is provided with a charger for uniformly charging the photosensitive drum, and an exposing unit for forming an electrostatic latent image by exposing the surface of the photosensitive drum with a pattern corresponding to an image to be outputted and removing the charge of the exposed portion. A developing unit is provided for applying toner to the surface of the photosensitive drum to form a toner pattern corresponding to the electrostatic latent image on the surface of the photosensitive drum.
In the developing unit, a developer in which carriers (magnetic particles) and toner are mixed is used, and in a state in which the developer is supplied between the photosensitive drum and a developing roller, a toner pattern is formed on the surface of the photosensitive drum by rotating the photosensitive drum and the developing roller. Here, when the temperature of the developer is increased, there are cases in which the toner deteriorates (melts) or adheres to members other than the photosensitive drum. In such a case, problems may occur such as defects being generated in an image to be formed, the apparatus being damaged, or the like. On the other hand, in order to increase the processing speed, it is necessary to increase the rotation speed of the developing roller and the like, and in this case, the friction heat accompanying this increases. Moreover, in order to maintain the developer in an appropriate state, a stirring mechanism for stirring the developer is also provided, and frictional heat is also generated during this stirring.
Therefore, in the image forming apparatus, a mechanism for cooling the developing unit is provided. Here, since the photosensitive drum and the developing roller are formed to be elongated in the direction of the rotation axes thereof, the developing unit is formed to be elongated. In addition, in an image forming apparatus that forms a color image, four sets of photosensitive drums and developing units are usually provided, one for each color, and it is necessary to cool each of them. Therefore, in order to reduce the size and cost of the entire apparatus, the structure of the cooling mechanism is required to be simple. For this reason, as this cooling mechanism, a cooling mechanism having a configuration in which cooling air (gas) flows in the longitudinal direction of the developing unit is used.
In a typical technique, there is an image forming apparatus provided with such a cooling mechanism. In this image forming apparatus, the developing unit is detachable from the main body, and ducts for respectively causing cooling air to flow to the main body side and the developing unit side are provided. In this case, when the developing unit is mounted, the cooling air can flow smoothly from the duct on the main body side to the duct on the developing unit side, and cooling air can flow smoothly along the longitudinal direction of the developing unit. As a result, the cooling efficiency of the developing unit can be improved.